1. Field of the Invention
The present invention relates to support a leg designed to support a plurality of floor panels at a predetermined interval from a floor slab, and to a double floor which is supported by these support legs. More particularly, the present invention relates to a floor panel support leg which stably and firmly supports the butted portions of a plurality of floor panels at a low position above the floor slab, and to a double floor which is supported by these support legs.
2. Description of the Related Art
In recent years, due to the introduction of a plurality of office automation machines not only in computer rooms, but also in ordinary offices, it has become necessary to arrange several types of communication cables and electric cables on the floor. In conventional offices, communication and power source plug sockets are provided on walls and pillars, and it is necessary to trail the connecting cables on the floor from the plug sockets to the place of equipment installation. Yet, when these cables are exposed on the floor, it is possible that during walking one's foot may inadvertently be caught and pull out a plug of a connecting cable, or there is the danger that a connecting cable may be 'severed by the pressure under other machinery or by the passage of a push cart, etc.
Thus, double floors called "free access floors" have been widely adopted in recently constructed buildings, and particularly in this type of office quarters. This type of double floor is explained by an example shown in FIG. 4. For example, a plurality of quadrangular floor panels 1 in each of which one side is in a range of from 150 to 1000 mm and the thickness is in a range of from 15 to 50 mm are prepared. A plurality of support legs are provided vertically on a floor slab 2 at intervals from each other approximately correspondingly to the length of one side of the floor panel 1. Then, the floor panels 1 are laid down on the floor slab 2 so that the respective corner portions of four adjacent floor panels 1 are supported by the tip of one support leg 3. By this means, space is created between the floor panels 1 and the floor slab 2, so that floor communication cables and electric power cables, or interface equipment for the distributors and employed equipment can be arranged in this space under the floor. Further, plug sockets can be provided on the floor panels near the installed machinery or apparatus, and the distance of the cables or the like which are exposed on the floor can be shortened to the minimum. Moreover, the floor panels 1 can be easily removably attached and changes in layout following installation can be adequately coped with.
Yet, since the double floor is arranged at a predetermined height from the floor slab in the aforementioned manner, the height from the surface of the floor to the ceiling is lowered in comparison to the ordinary floor design, so that one may feel an oppressive sensation. In the case of newly constructed buildings, however, in consideration of the height of the double floor, it is possible to execute in advance a design so as to make the height from the floor slab to the ceiling sufficiently high so as to thereby remove this feeling of oppression, but in the case where a double floor is installed in an already existing building, this feeling of oppression cannot be removed. Thus, it is desirable to have a low double floor with a height of, for example, 50 mm or less. For this purpose, if the height of the support leg which supports the floor panels is lowered, the height of the double floor also becomes low, so that not only it is possible to remove the feeling of oppression to thereby implement this double floor in existing buildings, but also it is possible to lower the height to the ceiling in the case of newly constructed buildings to thereby contribute to the effective utilization of space. As shown in FIG. 4, in the case where the support leg 3 is constituted by a lower pedestal 4 which is disposed on the floor slab 2, a screw shaft 5 provided at the center of this lower pedestal 4 so as to constitute a support column, a screw sleeve 6 to which this screw shaft 5 is screwed, and an upper pedestal 7 which has the screw sleeve 6 at its lower side and which supports the floor panels 1 at its top surface, the floor panels 1 can be supported at a low position with the lowered height of the screw shaft 5. Yet, for example, if the height of the support leg 3 is lowered so that the height of the double floor is made to be 50 mm or less, the thread-engagement portion of the screw shaft 5 and the screw sleeve 6 becomes correspondingly shorter, the support of the floor panels 1 becomes unstable, and the strength becomes insufficient. Thus, with the conventional pedestal support method, it has been impossible to make the height of the double floor approximately lower than 60 mm.
A double floor has been proposed where a plurality of mats of predetermined thickness are arranged on a floor slab with certain intervals between the adjacent mats; cables are made to pass through these intervals and the respective upper portions of the intervals are closed with a covering material; and a carpet is then laid over the mats and the intervals so as to cover them. In this way, by replacing the support legs and floor panels with the carpet and mats which support the carpet in plane, and by adjusting the thickness of the mats, it is possible to obtain a double floor with a height of 50 mm or less. As another example, a proposal has been made so that a support in which a plurality of height-adjustable columns at the underside of a thin tabular body of approximately the same size as a floor panel is provided in the form of an individual support unit in which one floor panel is fastened to and supported by one support. There are no pedestals, and the screw fitting member can be made long, with the result that it is possible to obtain a double floor with a height 50 mm or less.
Among these proposals, however, in the case of the former, since it is necessary to lay mats over the entire floor slab which forms the double floor and to fill the intervals between the mats with cover material, there is a defect that the number of parts becomes very large. Moreover, since the mats are spread over the floor slab, the manufacturing precision of the floor slab directly influences the finished product, it is necessary to give the floor slab an extremely flat finish, and much care must be taken to manufacture the floor slab. Furthermore, there is such a defect that there is an opening only for cables between the mats, and air conditioning cannot be conducted under the floor.
With regard to the latter proposal, since each floor panel is supported by an independent column, in the case where the level of the floor panels is adjusted, at least the columns of the four corners must be adjusted and the adjustment is troublesome. Further, it becomes necessary to redo the level adjustment whenever a change is made in the orientation of the floor panels. Furthermore, there is a defect that, when the floor panels are removed at the time of cable installation, the cables near the columns are easily moved, so that, when the floor panels are restored, the cables may become pressed under the columns to make the storage inconvenient, or the cables may be injured and broken.